Hypertension is a condition commonly associated with narrowing of the arteries. This causes blood to be pumped with excessive force against the artery walls. It is a sign that the heart and blood vessels are being overworked. If left untreated hypertension can cause serious cardiovascular disease. For example, the heart muscle can thicken (cardiac hypertrophy) and function abnormally, or dilate and contract less forcefully (dilated cardiomyopathy). High blood pressure can also cause injury to the brain, the eyes and/or the kidneys. Hypertensive patients are also at increased risk of having a stroke.
In vivo the renin/angiotensin system functions to regulate blood pressure. This system comprises the angiotensin I-converting enzyme (ACE) which catalyses the cleavage of inactive angiotensin I into the active vasoconstrictor, angiotensin II. ACE also catalyses the degradation of the vasodilator, bradykinin.
Various enzymatic hydrolysates and peptides derived from food protein have been reported to have ACE inhibitory activity.
In particular, Ono et al. (2003) report that a chum salmon hydrolysate, obtained using thermolysin, had ACE inhibitory activity. Thermolysin is a metalloendopeptidase with a specificity for peptide bonds on the N-terminal side of hydrophobic amino acids, and which is produced by Bacillus thermoproteolyticus).
Ohta et al. (1997) report that a hydrolysate obtained by hydrolysis of a chum salmon head with the commercial serine endopeptidase Biopurase SP10 (from Bacillus subtilis) had greater ACE inhibitory activity than hydrolysates prepared by digestion of the salmon head with any of the following commercial proteases: XP-415 (from Rhizopus delemar), Papain (from Carica papaya), DenazymeAP (from Aspergillus oryzae) or Denapsin2P (from Aspergillus niger).
However, neither Ono et al. nor Ohta et al. report the use of a bacillolysin in preparing anti-hypertensive fish protein hydrolysates.